Assuming that the flight departs from the UK, the arrival airport will be Canova (Treviso) airport for Ryanair flights, or Marco Polo airportfor any other operator.
From Marco Polo, bus services are here:
http://www.veniceairp...ti/autobus?m=01020202
but a Alilaguna ticket, on the 'Orange Line' is probably the best option . It can be pre-booked online for €12 single
http://tinyurl.com/38pzgz5
or €24 return
http://tinyurl.com/3ygnue6
Water taxi details are here:
http://www.motoscafivenezia.it/eng/index.php
Public transport information for Canova/Treviso Airport can be found here:
http://tinyurl.com/3a8vcdg
Chris